Threatened, missed, incomplete and complete miscarriage — Rapid

Synopsis

Distinguish early-pregnancy bleeding with ongoing viability from missed, incomplete and complete miscarriage using safe ultrasound criteria while continuing to exclude ectopic pregnancy.

Threatened miscarriage means vaginal bleeding with a confirmed intrauterine pregnancy that remains viable; the cervix is usually closed and many pregnancies continue.
Missed miscarriage means an intrauterine pregnancy has stopped developing but pregnancy tissue remains, often with little bleeding and a closed cervix.
Incomplete miscarriage means some intrauterine pregnancy tissue has passed but tissue remains, usually with continuing bleeding, cramping and an open cervix.
Complete miscarriage means all intrauterine pregnancy tissue has passed and the uterus is empty, but only call it complete when prior imaging documented intrauterine location or ectopic follow-up is complete.
Transvaginal ultrasound is the diagnostic standard for location and viability; use CRL and mean sac diameter with minimum seven-day repeat scans when findings are uncertain.
Do not use last menstrual period alone to decide a heartbeat should be visible, and explain that waiting for a repeat scan does not harm pregnancy outcome.
For threatened miscarriage with scan-confirmed intrauterine pregnancy, bleeding and at least one previous miscarriage, offer micronised vaginal progesterone 400 mg twice daily; if heartbeat is confirmed continue to 16 weeks.
From June 2026, do not offer anti-D for threatened miscarriage or miscarriage through 11+6 weeks; at 12+0 to 12+6 weeks apply the new bleeding and management-specific recommendations.

Key red flags

A positive pregnancy test with unilateral pain, shoulder-tip pain, collapse or an empty uterus may be ectopic pregnancy even if tissue or clots have passed.

Heavy ongoing bleeding with tachycardia, hypotension, pallor or syncope requires emergency haemorrhage care and may need urgent uterine evacuation.

Fever, uterine tenderness, offensive discharge or systemic illness suggests infected miscarriage or retained tissue and needs urgent antibiotics and source control.

A single borderline scan without the NICE repeat interval cannot safely diagnose miscarriage and risks treatment of a viable pregnancy.

Investigation priorities

Transvaginal ultrasoundFirst step

Confirm location, viability, retained tissue and adnexal or free-fluid findings.

Management branches

First assessmentStabilise, locate and test viability

A patient presents with pain or bleeding in early pregnancy.

Assess haemodynamics, bleeding, pain, ectopic and infection features and escalate shock, peritonism, sepsis or uncontrolled bleeding immediately.
Obtain pregnancy testing, expert transvaginal ultrasound and targeted bloods, adding consented speculum examination where it answers bleeding or tissue questions.
Classify only when location and safe viability criteria support it; otherwise use PUL or uncertain-viability follow-up with exact repeat intervals.

Key medicines

Micronised vaginal progesterone for threatened miscarriageInsert 400 mg vaginally twice daily when scan confirms an intrauterine pregnancy, current bleeding is present and at least one previous miscarriage occurred; if fetal heartbeat is confirmed continue to 16 completed weeks.Do not use for PUL, bleeding without prior miscarriage or recurrent miscarriage without current bleeding; confirm location first and reassess worsening pain, bleeding or collapse urgently.

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